Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Aqueous”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Selective and “turn-off” fluorimetric detection of mercury(II) based on coumarinyldithiolane and coumarinyldithiane in aqueous solution

Graphical abstract: Visual fluorescence emission of probe 3a. - Highlights: • Five novel coumarin-based fluorescent probes were developed. • A reasonable reaction mechanism was proposed and verified. • All the probes showed excellent optical properties. - Abstract: In this work, five novel coumarin-based fluorescent probes for mercury ions were developed. The recognition of mercury ions was performed via the mercury(II)-promoted desulfurization of the probes and a reasonable reaction mechanism was proposed and verified by thin layer chromatography (TLC), {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) and fluorescence intensity measurements. All the probes showed excellent optical properties and exclusively distinguish mercury ions from various metal ions in aqueous solutions at pH 7.4. The linear response of the fluorescence emission intensity for all the probes to the concentration of mercury ions was obtained over a wide range of 0.06–1.5 μM (0.06–0.9 μM for probe 3e). In addition, the biological toxicity and the confocal fluorescence images of probe 3a were also tested on MCF-7 cells.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Reliable hydrogen production from methanol photolysis in aqueous solution by a harmony between In and Zn in bimetallic zinc indium sulfide

Highlights: • Band-gaps in Zn{sub x}In{sub y}S{sub z} particles were shorten. • Hydrogen production by methanol photolysis was the best on ZnInS{sub 2.5}. • Recombination between electrons and holes during methanol photolysis became long on ZnInS{sub 2.5}. - Abstract: This study focuses on hydrogen production by methanol photolysis using zinc indium sulfide (Zn{sub x}In{sub y}S{sub z}). The X-ray diffraction identified that the synthesized Zn{sub 2}InS{sub 2.5} and ZnInS{sub 2.5} particles have a hexagonal Zn{sub 3}In{sub 2}S{sub 6} structure, but when In of twice amount against Zn is coexisted, the particle exhibits a perfect hexagonal ZnIn{sub 2}S{sub 4} structure. The results in ultra-violet absorption and X-ray photoelectron spectroscopy analysis confirmed that the band-gaps of Zn{sub x}In{sub y}S{sub z} particles decrease depend on the coexistence of In. However, the photocurrent which related to the life time of excited electrons was no correlation with the Zn/In molar ratio, and it was the highest on ZnInS{sub 2.5} particle with a ratio of Zn:In = 1:1. Eventually, the hydrogen production by methanol photolysis in aqueous solution was the best on ZnInS{sub 2.5} particle. This result gives ultimately relevant that the recombination between electrons and holes during methanol photolysis could be suppressed on bimetallic ZnInS{sub 2.5} particle.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A semi-empirical molecular statistical thermodynamic model for calculating standard molar Gibbs energies of aqueous species above and below the critical point of water

An increasing number of industrial applications rely on controlling solutes in water above and below its critical point. Processes such as hydrothermal synthesis, steam power generation and ultra-high enthalpy geothermal power are all influenced by factors such as mineral precipitation, pH and solute speciation. Here, the supercritical point of water is remarkable in that slight changes in temperature and pressure can cause dramatic changes in some solute properties. Here, it was found that our approach reliant on molecular statistical thermodynamic expressions for hard sphere (HS), ion-dipole and dipole-dipole interactions via mean spherical approximation (MSA) provided excellent agreement to available experimental data. In addition to model parameters having some physical meaning, this approach used less adjustable parameters than the well-known Helgeson-Kirkham-Flowers (HKF) model. Furthermore, the model was used to obtain standard thermodynamic values for HCl 0 (aq), KCl 0 (aq) and NaOH 0 (aq) ion pairs. In total, modeling parameters for 10 different aqueous species were obtained to demonstrate the capabilities of the approach.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

An organic bifunctional redox active material for symmetric aqueous redox flow battery

Symmetric redox flow batteries utilizing a single redox active material as catholyte and anolyte, offer a plausible and unique strategy to alleviate cross-contamination issues during cycling, making them an ideal energy storage device for large scale applications. In this work, a low-cost riboflavin organic molecule is coupled with a 2,2,6,6-Tetramethylpiperidinyl-N-oxyl (TEMPO) radical molecule to form a single Riboflavin-TEMPO (RIBOTEMPO) bifunctional redox active material, which is used in both aqueous anolyte and catholyte. Cyclic voltammetry analysis of the combined molecule displays electrochemically reversible reactions for the redox couples at 0.72 V and 0.51 V versus Hg/Hg2SO4, leading to a theoretical cell voltage of 1.23 V. A symmetric cell testing demonstrated over 100 consecutive charge/discharge cycles with nearly 80% coulombic efficiency and capacity retention of 44.7% at a current density of 2.5 mA cm(-2). By utilizing a pH neutral supporting electrolyte, a lowcost, safe, and environmental-friendly redox flow battery is achieved. This work provides a pathway for the design and development of bifunctional redox active molecules for symmetric battery applications.

25 ENERGY STORAGE↗
DOE OSTI2024

Investigation of pyruvic acid photolysis at the air-liquid interface as a source of aqueous secondary organic aerosols

Pyruvic acid (PA) is a ubiquitous 2-oxocarboxylic acid in the atmosphere. Its photochemical process at the air-liquid (a-l) interface has been suggested as an important source of aqueous secondary organic aerosols. Here, we investigated the photochemical reaction pathways of PA at the a-l interface using synchrotron-based vacuum ultraviolet single-photon ionization mass spectrometry (VUV SPI-MS) coupled with the System for Analysis at the Liquid Vacuum Interface (SALVI) microreactor. Results from mass spectral analysis and the determination of appearance energies (AEs) indicate that photolysis of PA can generate radicals, then they recombine with carboxylic acids and simple molecular oligomers. Furthermore, the preliminary products could form larger oligomers via radical reaction or esterification in the presence of hydroxyl and carboxyl functional groups. Mass spectral comparison shows that most photochemical reactions would complete within 4 h. The expanded photochemistry-driven reaction flowchart of PA is proposed based on the newly discovered products. Our results reveal that the interfacial PA photochemical reactions have different mechanisms from the bulk liquid due to the interfacial properties, such as molecular density, composition, and ion concentration. Our findings show that in situ mass spectral analysis with bright photon ionization is useful to elucidate the contribution of a-l interfacial reactions leading to aqSOA formation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Aqueous Phase Hydrodeoxygenation of Phenol over Ni 3 P-CePO 4 Catalyst

Unsupported Ni 3 P-CePO 4 catalysts were prepared, characterized their catalytic performance in hydrodeoxygenation (HDO) was investigated using aqueous solution of phenol as the feed. The addition of CePO 4 resulted in enhanced HDO activity with the maximum activity at a Ce:Ni ratio of 3:10. The CePO 4 improved the dispersion of Ni 3 P significantly and led to enhanced hydrogenation activity. CePO 4 provided dehydration sites as well through its surface acidity (mainly Lewis acid).

Ni3P, CePO4, Aqueous phase, Hydrodeoxygenation, Ph↗
DOE OSTI2023

High-Temperature Reaction Kinetics of the e aq – and HO 2 • Radicals with Iron(II) Ions in Aqueous Solutions

Pulsed electron radiolysis was used to determine the chemical reaction kinetics and Arrhenius parameters for iron(II) reactions in aqueous solutions under irradiation. The second-order Fe 2+ reactions with the hydrated electron (e aq – ) and the perhydroxyl radical (HO 2 • ), arising from water radiolysis, were measured to high temperatures using custom-built flow-through cells with a multichannel optical detection system. The reaction with the HO 2 • radical was found to proceed via the formation of a metal-ion adduct species, Fe 2+ –HO 2 • . Additionally, the adduct’s molar extinction coefficient and its first-order decay rate coefficients are reported.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

An Extremely Stable and Soluble NH 2 -Substituted Anthraquinone Electrolyte for Aqueous Redox Flow Batteries

Aqueous redox flow batteries require long-term stable redox molecules for electrical energy storage. Anthraquinones, especially ether bond-decorated ones, experience two dominant decomposition pathways, including side-chain loss and anthrone formation. Here, with the aid of DFT calculations, we designed an anthraquinone (3-NH 2 -2-2PEAQ) bearing an ether substituent and a neighboring NH 2 group, which suppresses both of these decomposition mechanisms and exhibits a high solubility of 1.1 M. When paired with ferrocyanide in a full cell, this anthraquinone, at a concentration of 1.0 M, can operate at greater than 1 V with an extremely low capacity fade rate of 0.01%/day and a Coulombic efficiency above 99.8% while cycling for over a month. The synergistic effects of the ether and parent amino substituents are extremely sensitive to the precise substitution pattern of the anthraquinone. This study demonstrates the effectiveness of the judicious use of DFT-based prediction in rapidly identifying promising candidate electrolytes from a large chemical space.

25 ENERGY STORAGE↗
DOE OSTI2020

Amorphous Manganese Oxides: An Approach for Reversible Aqueous Zinc-Ion Batteries

Crystalline manganese oxides have attracted the most attention in aqueous zinc-ion batteries due to their diverse nanostructures and low cost. However, extensive studies on amorphous manganese oxides are lacking. Here in this paper, we report a mesoporous amorphous manganese oxide (UCT-1-250) as a cathode material with high capacity (222 mAh g –1 ), good cyclability (57% capacity retention after 200 cycles), and an acceptable discharge plateau (between 1.2 and 1.4 V). An approach to mechanistic studies was performed by comparison of UCT-1-250 and other crystalline manganese oxides through electrochemical, elemental, and structural analyses. An in situ conversion to ZnMn 2 O 4 spinel phase after initial cycling contributes to the high performance. The irreversible capacity fading is due to the formation of the woodruffite phase.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Ball Milling-Enabled Fe 2.4+ to Fe 3+ Redox Reaction in Prussian Blue Materials for Long-Life Aqueous Sodium-Ion Batteries

Aqueous Na-ion batteries using Prussian blue materials have inherent advantages on safety, material sustainability, and economic cost. However, it is challenging to obtain long term cycling stability because many redox reactions have poor intrinsic stability in water. In this report we demonstrate reversible Fe 2.4+ to Fe 3+ redox reaction of Prussian blue electrodes cycled in 17 m NaClO 4 water-in-salt electrolyte. The cubic phase c-Na 1.17 Fe[Fe(CN) 6 ]·0.35H 2 O) derived from monoclinic Prussian blue (m-Na 1.88 Fe[Fe(CN) 6 ]·0.7H 2 O) through ball milling delivers excellent cycling stability of >18,000 cycles with >90% capacity retention at 10C rate. The specific capacity is ~75 mAh/g and ~67 mAh/g at 1C and 10C rate, respectively. Systematic characterizations including electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy have verified the phase transition and iron oxidation state evolution, revealing the mechanism that enables the material’s high rate and long durability as the battery cathode.

25 ENERGY STORAGE↗
DOE OSTI2025

Modulating Solvation Structure in Concentrated Aqueous Organic Redox Flow Battery Electrolyte for Solubility and Transport Enhancement via Polycomplex Ion

Aqueous organic redox flow batteries hold great promise as a technology for creating economical grid energy storage using sustainable materials. Nonetheless, the solubility limit presents a universal barrier for all redox-active organic molecules. In this paper, a new approach is proposed to surpass the solubility limit by manipulating the solvation structure with polycomplex ion additives (PIA). Using poly(3,4-ethylenedioxythiophene) polystyrenesulfonate colloids as one example, its role in dismantling the rigid supramolecular clusters within the highly concentrated 7,8-dihydroxyphenazine-2-sulfonic acid electrolyte is investigated. 1 H and 23 Na NMR spectra and molecular dynamics simulation studies demonstrate that the bipolar structure of the PIA effectively disrupts the aggregations of DHPS and Na + ion in the highly concentrated anolyte, thus rendering a more flexible solvation structure and less restrictive ion transport, leading to substantially improved battery performance of an AORFB cell. The anolyte with PIA achieved 1.6 M and 74.3 Ah L –1 anolyte energy capacity.

25 ENERGY STORAGE↗
DOE OSTI2025

Photochemical and Cloud and Aerosol Aqueous Contributions to Regionally-Emitted Shipping and Biogenic Non-Sea-Salt Sulfate Aerosol in Coastal California

Aerosol nonsea-salt sulfate (NSS sulfate) forms in the atmosphere by secondary reactions of emissions from marine phytoplankton and shipping, with gas-phase as well as cloud and aerosol aqueous reactions controlling production. Twelve months of Atmospheric Radiation Measurements (ARM) during the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE) at Scripps Pier in La Jolla, California, showed the highest NSS sulfate mass concentrations occurred for the northwesterly back-trajectories over 64% of the year, with an average of 0.90 μg/m 3 that contributed 76% of annual NSS sulfate concentration. Multiple Linear Regression (MLR) and a refractory black carbon tracer method attributed 76–80% of the regionally emitted sulfur dioxide (SO 2 ) sources of submicron NSS sulfate to marine biogenic emissions and 20–24% to shipping emissions. MLR for oxidation processes explained 21% of the variability with Downwelling Shortwave Radiation (DSW) driving photochemical reactions to account for 34% of annual regional sulfate production, Upwind Cloud Vertical Fraction (UCVF) controlling cloud-associated oxidation to account for 29%, and relative humidity (RH) describing aerosol-phase oxidation to account for 36%. NSS sulfate was correlated moderately to UCVF during April-June and August but to RH in October-January. These findings show the apportionment of SO 2 emissions to biogenic and shipping sources and provide observational constraints for the mechanisms for sulfate production from SO 2 in the atmosphere.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Rapid Removal of Mercury from Aqueous Solutions Using Thiol Functionalized Zn-doped Biomagnetite Nanoparticles

The surfaces of Zn-doped biomagnetite nanostructured particles were functionalized with (3-mercaptopropyl)trimethoxysilane (MPTMS) and used as a high-capacity and collectable adsorbent for the removal of Hg(II) from water. Fourier transform infrared spectroscopy (FTIR) confirmed the attachment of MPTMS on the particle surface. The crystallite size of the Zn-doped biomagnetite was {approx}17 nm, and the thickness of the MPTMS coating was {approx}5 nm. Scanning transmission electron microscopy and dynamic light scattering analyses revealed that the particles formed aggregates in aqueous solution with an average hydrodynamic size of 826 {+-} 32 nm. Elemental analyses indicate that the chemical composition of the biomagnetite is Zn{sub 0.46}Fe{sub 2.54}O{sub 4}, and the loading of sulfur is 3.6 mmol/g. The MPTMS-modified biomagnetite has a calculated saturation magnetization of 37.9 emu/g and can be separated from water within a minute using a magnet. Sorption of Hg(II) to the nanostructured particles was much faster than other commercial sorbents, and the Hg(II) sorption isotherm in an industrial wastewater follows the Langmuir model with a maximum capacity of {approx}416 mg/g, indicating two -SH groups bonded to one Hg. This new Hg(II) sorbent was stable in a range of solutions, from contaminated water to 0.5 M acid solutions, with low leaching of Fe, Zn, Si, and S (<10%).

36 MATERIALS SCIENCE↗
DOE OSTI2010

Structure of the UO[subscript 2][superscript 2+]-SO[subscript 4][superscript 2-] Ion Pair in Aqueous Solution

The structure of the ion pairs formed in aqueous uranyl sulfate solutions has been investigated with high-energy X-ray scattering. Sulfate binds to the uranyl as a monodentate ligand in equimolar solutions. The geometry of the ion pair is very similar to configurations found in crystalline structures; in particular, the U-O-S angle is bent in solution as well as in the solid state. It can therefore be concluded that an U-O-S angle of 143{sup o} is an intrinsic property of the uranyl sulfate bond and not due to packing effects or interaction with the water in the primary solvation shell.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Molecular Mechanism of Specific Ion Interactions Between Alkali Cations and Acetate Anion in Aqueous Solution: A Molecular Dynamics Study

Specific ion interactions between the alkali cations (i.e., Li+, Na+ and K+) and an acetate anion in aqueous solution were studied using molecular dynamics simulation techniques and polarizable potential models. The ions-acetate systems were used as a model for understanding the interactions between ions and protein surfaces. We computed free energy profiles for different ion pairs using constrained mean force methods. Upon analyzing the computed free energy profiles for the Na+/K+-acetate ion-pairs, we observed a deeper contact ion minimum and also a larger association constant for the Na+-acetate pair compared to the corresponding K+-acetate pair. These observations help to demonstrate the preferential binding of Na+ over K+ to protein surfaces.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Dissociative Binding of Carboxylic Acid Ligand on Nanoceria Surface in Aqueous Solution: A Joint in Situ Spectroscopic Characterization and First-Principles Study

Carboxylic acid is a common ligand anchoring group to functionalize nanoparticle surfaces. Its binding structures and mechanisms as a function of the oxidation states of metal oxide nanoparticle surfaces are not well characterized experimentally. We present an in situ sum frequency generation vibrational spectroscopy (SFG-VS) study on the binding of deuterated acetic acid on ceria nanoparticles in the aqueous solution. In the SFG experiment, ceria nanoparticles were deposited on the flat surface of a CaF2 hemisphere in contact with acetic acid solutions. While the ceria nanoparticle deprotonated the acetic acid, the CaF2 surface could not. Thus, the binding of the deprotonated acetic acid on ceria can be selectively probed. SFG spectra revealed that the binding modes of the carboxylate group depend on the oxidation states of the ceria surfaces. SFG polarization analysis suggested that the bidentate chelating and bridging binding modes co-exist on the reduced ceria surfaces, while the oxidized ceria surfaces are dominated by the bidentate bridging mode. The direct spectroscopic evidence helps to clarify the binding structures and mechanisms on the ceria nanoparticles. Furthermore, the middle-infrared (IR) transparent CaF2 and its chemical inertness make CaF2 and similar substrate materials good candidates for direct SFG-VS measurement of nanoparticle surface reactions and binding chem-istry.

aqueous solutions↗
DOE OSTI2013

Coordination and Hydrolysis of Plutonium Ions in Aqueous Solution using Car-Parrinello Molecular Dynamics Free Energy Simulations

Car-Parrinello molecular dynamics (CPMD) simulations have been used to examine the hydration structures, coordination energetics and the first hydrolysis constants of Pu3+, Pu4+, PuO2+ and PuO22+ ions in aqueous solution at 300 K. The coordination numbers and structural properties of the first shell of these ions are in good agreement with available experimental estimates. The hexavalent PuO22+ species is coordinated to 5 aquo ligands while the pentavalent PuO2+ complex is coordinated to 4 aquo ligands. The Pu3+ and Pu4+ ions are both coordinated to 8 water molecules. The first hydrolysis constants obtained for Pu3+ and PuO22+ are 6.65 and 5.70 respectively, all within 0.3 pH units of the experimental values (6.90 and 5.50 respectively). The hydrolysis constant of Pu4+, 0.17, disagrees with the value of -0.60 in the most recent update of the Nuclear Energy Agency Thermochemical Database (NEA-TDB) but supports recent experimental findings. The hydrolysis constant of PuO2+, 9.51, supports the experimental results of Bennett et al. (Radiochim. Act. 1992, 56, 15). A correlation between the pKa of the first hydrolysis reaction and the effective charge of the plutonium center was found.

Actinide↗
DOE OSTI2014

Ewald Summation Approach to Potential Models of Aqueous Electrolytes Involving Gaussian Charges and Induced Dipoles: Formal and Simulation Results

We present a detailed derivation of the complete set of expressions required for the implementation of an Ewald summation approach to handle the long-range electrostatic interactions of polar and ionic model systems involving Gaussian charges and induced dipole moments with a particular application to the isobaricisothermal molecular dynamics simulation of our Gaussian Charge Polarizable (GCP) water model and its extension to aqueous electrolytes solutions. The set comprises the individual components of the potential energy, electrostatic potential, electrostatic field and gradient, the electrostatic force and the corresponding virial. Moreover, we show how the derived expressions converge to known point-based electrostatic counterparts when the parameters, defining the Gaussian charge and induced-dipole distributions, are extrapolated to their limiting point values. Finally, we illustrate the Ewald implementation against the current reaction field approach by isothermal-isobaric molecular dynamics of ambient GCP water for which we compared the outcomes of the thermodynamic, microstructural, and polarization behavior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗